Node

A node is a device connected to a blockchain network which performs one or more critical functions for the maintenance of the decentralized system. In its most basic form, a node stores a full or partial copy of the distributed ledger (blockchain) and participates in the validation, propagation and synchronization of new transactions and blocks. It is an essential piece to guarantee the integrity, censorship resistance, and network availability.

There are different types of nodes depending on their function:

• Full node: keeps a complete copy of the blockchain history and validates all transactions according to the rules of consensus.
• Light node: Download only partial information (such as headers) and rely on full nodes for verification.
• Validator node: actively participates in the creation and validation of blocks (in PoS or DPoS).
• Mining Node: in blockchains with PoW, it competes to add new blocks solving computational problems.
• File Node: Retains all history, including intermediate states, useful for audits or indexers.

In networks such as Ethereum, Bitcoin, or Polkadot, nodes constantly communicate information about blocks, pending transactions (mempool), consensus events and network updates. Its decentralization is essential to avoid single points of failure, guarantee resistance to manipulation and offer verifiable transparency.

Anyone can run a node, allowing for an open architecture, although its technical and economic maintenance varies depending on the network. Running a node provides independence, sovereignty over verification and, in some cases, economic rewards or the right to vote in on-chain governance systems.